Changes in non‐structural carbohydrates in olive (Olea europaea) leaves during root zone salinity stress

Abstract

Self‐rooted olive (Olea europaea L.) plants were grown in hydroponics at various NaCl concentrations (from 0 to 200mM) for 28 to 32 days followed by 28 to 30 days of relief from salinity over two growing seasons. Olive leaves accumulated both glucose and mannitol during the period of salinity stress. The concentrations of fructose, myo‐inositol, galactose, galactinol, sucrose, raffinose, and stachyose were not significantly affected by salinity. Starch content was decreased by salinity. The mannitol/glucose and mannitol/soluble carbohydrates ratios increased as the external NaCl concentration was increased, but returned to the control levels during the relief period. The increase in mannitol or glucose molar concentrations, expressed on a leaf tissue water basis, was partially due to a reduction in leaf tissue water content under salinity stress. However, an increase in mannitol concentration was also observed when expressed on a dry weight basis. The accumulation of mannitol in leaf tissue preceded any reduction in leaf area rate or net assimilation rate. The increase in leaf mannitol or glucose concentration was positively correlated with the increasing level of salinity at the root zone, but not with the accumulation of Na+ in the shoot. The role of mannitol. a potential osmoregulator in leaf mesophyll during salinity stress, is discussed in relation to the complex carbohydrate composition of olive leaves.

Changes in water status and osmolyte contents in leaves and roots of olive plants (Olea europaea L.) subjected to water deficit

“…At the maximum level of water deficit, mannitol content was 1.3 times higher in leaves of SP than in CP, confirming that this alditol plays a key role in osmotic adjustment of leaf tissues during water deficit. The increased foliar content of mannitol in olive leaves could be related to an increased activity of mannose-6-phosphate reductase (M6PR) and a decreased activity of mannitol dehydrogenase (MDH), which are the two key enzymes involved in the biosynthesis and catabolism of this sugar (Tattini et al 1996). In thin roots (c) during the experimental period.…”

“…Among fruit tree species, olive tree is able to tolerate a broad range of adverse environmental factors, including the low availability of water in soil (Bacelar et al 2007), salinity (Tattini et al 1996), chilling and high temperature stress (Bongi and Long 1987) and high irradiance levels (Sofo et al 2004).…”

Complementary responses of morphology and physiology enhance the stand‐scale production of a model invasive species under elevated CO2 and nitrogen

“…In contrast, under elevated CO 2 , stronger CO 2 diffusion gradients and increased WUE i would have mitigated these effects, at least within the salinity range observed (4-18 ppt). Furthermore, it is possible that an enhanced availability of non-structural carbohydrates under elevated CO 2 (Cheng, Moore, & Seemann, 1998) provided an energy subsidy for P. australis to mitigate the osmotic stress associated with salinity (Tattini, Gucci, Romani, Baldi, & Everard, 1996).…”

The Amino Acid Metabolic and Carbohydrate Metabolic Pathway Play Important Roles during Salt-Stress Response in Tomato

“…Haitao et al (2013) demonstrated that arginase expression modulates abiotic stress tolerance in Arabidopsis. It was suggested by Tattini et al (1996) that in olive leaves, mannitol and glucose play an active role in the osmotic adaptation of plants to salinity. These studies clearly demonstrate that the protein metabolism and carbohydrate metabolism play very important roles in the stress response.…”